The invention relates to a snap-hook, notably for mountain climbing, comprising a C-shaped metallic body, having a first end provided with a male securing part, and a second end for articulation of a mobile finger around a pivoting spindle between a closed position and an open position, said finger comprising:
a female securing part arranged opposite the pivoting spindle to cooperate with the male securing part in the closed position, PA1 a first return spring to return the finger to the closed position, PA1 a locking ring mounted with limited rotation coaxially around the finger between a first locking position and a second unlocking position, said ring comprising memory means to keep it in the second unlocking position so long as the finger is open, PA1 and a second return spring to return the locking ring to the first locking position when the finger is closed.
Known snap-hooks make use of a rotary locking ring, kept in the locking position by the elastic force of the return spring. To open the snap-hook by pivoting of the finger towards the inside of the body, the ring first has to be turned to the unlocking position. The angular travel of the ring between the two locking and unlocking positions is relatively large, notably about 90.degree., which makes handling with the thumb and forefinger of one hand complicated. Another drawback concerns the safety which is not total, for a large friction of the rope may result in untimely unlocking of the ring, and cause undesired opening of the finger.
To improve the safety, another known snap-hook proposes reinforcing the unlocking movement of the ring, by combining a first translation movement with a second rotational movement to the unlocking position. The ring however still remains subjected to elastic forces, which does not exclude untimely opening of the finger in the presence of a very large friction of the rope. Handling such a snap-hook with one hand is moreover difficult.
A third type of snap-hook exists with a manual locking ring with bayonet, which is bistable, that is to say that it does not automatically return to the locking position when the finger is reclosed. Safety is not assured if the user forgets to lock the ring manually.